Well! That's why Mobil 1 invented their high mileage version (75K+). I had leaks too until I switched to this version that contains a seal improving ingredient. This type of seal technology is available by itself, but Mobil 1 does it in one convenient package. I've noticed no leaking since introducing Marvel Mystery. I'm now at 750 miles and am using less than half the oil I'd expect. I'll keep you posted.